Shield Spearman x 50 w/ FC & Std of Discipline
Detachment of Swordsman x20
Detachment of Swordsman x20
Fills out core perfectly in a 2500pt game
Granted Empire parent units will become 'mini stars' with the pile of characters that will be needed for them but with special abilities passing on I foresee a trend of big units with detachments ranging from 15-30.
Add a warrior priest to give the all three hatred. Add a witch hunter to give them fear/terror resistance. Add a captain or general to let them make break tests like lizards. Random wizard/priest/wizardmobile buffs to add to the combat killey-ness.
Put the detachments 1" back and counter charge to lock up the enemy and hold on until a steamtank or demigryph unit can finish the job.
Overall I believe that detachments will become commonplace again (as in the past book noone ran them around here.)